PHMSA alleges that the Irving, Texas-based energy company failed to properly address known seasonal flooding risks to the safety of its pipeline system, including excessive river scour and erosion, and to implement measures that would have mitigated a spill into a waterway.

The agency also says that ExxonMobil failed to establish written procedures for its staff to take prompt and effective action to protect the Silvertip pipeline from floods and other natural disasters, and to minimize the volume of oil released from any section along the pipeline’s system.

“It is our priority to ensure that America’s transportation system is the safest in the world,” said U.S. Transportation Secretary Ray LaHood. “This system includes the nation’s 2.6 million miles of pipelines and it is our responsibility to see that those who operate them are held accountable for adhering to federal safety standards.”

The Silvertip Pipeline is a 12-inch pipeline approximately 69 miles in length and transports crude oil from the Silvertip station in Elk Basin, Wyo., to an ExxonMobil Refinery in Billings, Mont. The pipeline's failure on July 1, 2011 resulted in the release of 1509 barrels of crude oil during excessive flooding and adverse weather conditions.